While the talk of caffeine and safety has mostly centered around energy drinks (including those death reports linked to Monster Energy Drinks and 5-Hour Energy), it seems that the conversation has ignored the coffee giants of America. And according to the American Chemical Society’s study, a grande cup of coffee from Starbucks has 330 milligrams of caffeine — in comparison, a 5-Hour Energy drink has 215 milligrams of caffeine. And the amount of caffeine most people agree upon to be safe is just a tad higher at 400 milligrams per day. (However, as the study points out, the FDA hasn’t officially declared a ruling on how much caffeine is safe.)

However, Starbucks has spoken out against the study, and was quoted by the Daily Mail as saying that the chain’s grande size only contains 160 milligrams of caffeine. (Business Insider also notes past studies that show Starbucks’ coffee contains more caffeine than Dunkin’ Donuts’ coffee.) And of course, there’s one big caveat to all the hoopla; as the scientists note, everyone reacts differently to caffeine. Says the study:

“Fifty percent of the caffeine a person takes in gets cleared from the body, on average, in five hours. But studies have shown this rate can vary because of other drug use: Women taking oral contraceptives break down caffeine slower than those not on a contraceptive pill, and people who smoke process the stimulant faster than those who don’t. Genetics also plays a big role in how a person reacts to caffeine. For example, men metabolize caffeine faster than women.”

But if our Starbucks may also make us as jittery as an energy drink… what are we supposed to do to get through the work day?

The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.